Design of a Hierarchical Ternary Hybrid for a Fiber-Shaped Asymmetric Supercapacitor with High Volumetric Energy Density

A novel fiber-shaped supercapacitor is created with high volumetric energy density by designing an asymmetric configuration and integrating multiple functional components for electrodes. More specifically, a ternary hybrid fiber is prepared as a positive electrode by growing MnO₂ nanosheets onto a conducting polymer-coated carbon nanotube fiber; an ordered microporous carbon/carbon nanotube hybrid fiber is made as a negative electrode; and the hybrid positive and negative fibers are assembled into a fiber-shaped asymmetric supercapacitor. It shows a high operating voltage of 1.8 V, compared with 0.8–1.0 V of their conventional counterparts based on aqueous gel electrolytes; in particular, it produces an energy density as high as 11.3 mWh/cm³ which is on par with the thin-film lithium-ion batteries. It also exhibits remarkable cyclic stability and good rate performance. Due to the unique fiber shape, it can be woven or knitted into flexible power textiles.